BIOGAS PRODUCTION PLANT - HUMIX SYSTEM
Code:Organic biomass recovering, stabilization and composting.
Composting is the aerobic thermophilous process involving the degradation of organic substances in controlled conditions. Insufflating air into the pile of waste starts reactions that produce heat, which, if maintained in the pile, makes it possible to reach very high temperatures.
The high temperatures for prolonged contact periods make it possible to accelerate the processes of degradation and obtain a biologically stable product, evaporating a large quantity of water, and sanitizing the material.
A quality compost can be obtained using agricultural and food waste, green waste and sludge from water treatment; through the stabilization of the organic matrix it is possible to produce fuel derived from waste from the dry fraction of solid urban waste or waste obtained from separate collection.
There are two phases in the composting process: the first, called high rate, is characterised by the intense degradation of the organic components of the waste, and the second, called curing rate, in which the slow stabilization reactions develop. The high rate is often done in closed biocells in a controlled environment as the process is faster, safer and more uniform; as an alternative, the high rate can be implemented with the traditional system using barnyards with an aerated bed and/or using compost turning machines. The curing rate however is always done in a covered barnyard.
Various types of machines are used in composting plants.
A primary triturator shreds the material to the optimal size. A primary sieve is used for the first refining of the material. A mixer homogenizes the various types of waste, preparing them for fermentation. The air required for fermentation can be supplied through forced ventilation systems or by using compost turning machines which also reduce the compactness of the material.
The stabilized material is subjected to a final sieving and further refining.
THE IDROENGINEERING PROCESS
To obtain a quality compost it is essential to guarantee homogeneous and continuous ventilation throughout the mass. IDROENGINEERING SRL has designed a modular system of calibrated nozzles for the regular and optimal distribution of the air, allowing the homogeneous fermentation of all the material.
The bed made with modular plastic elements covered with reinforced concrete is quick and easy to install, and is also suitable for heavy vehicular traffic (effective loading capacity 10,000 kg/m2) providing excellent ventilation.
The entire plant, from the stocking section to the curing section is kept under a vacuum to prevent bad smells getting out. Any bad smelling air is blown back with fans in the ventilated bed and then sucked up and treated in a scrubber and biofilter. The air cleaner system makes it possible to eliminate bad smells, ammonia and any other contaminants.
The sewage from pre-treatment and fermentation areas is processed in an SBR (sequencing batch reactor), which, through a biological nitrification/denitrification treatment with activated sludge, makes it possible to eliminate the ammonia nitrogen from the percolate.
The sewage flowing out of the SBR is used again in the fermentation areas, to maintain the desired level of humidity; the sewage contains vital bacterial flora and it is sucked onto the fermenting waste to provide an inoculums effect.
STABILIZATION IN BIOCELLS
The biocell plant is particularly suitable for the production of quality compost. The biocell is a closed system which lets you check the critical parameters that control the process and allows the fermentation to develop in a regular and uniform way throughout the biomass. In this way, in a short lapse of time, you can obtain an excellent degree of stabilization of the waste. The automated suction/ventilation system lets you reduce the volumes of waste air to process. After leaving the biocell the material requires a curing period so the substances, that decay slowly, can stabilise. Usually the maturing is done in an aerated barnyard, with the insufflation of air and/or using a compost turning machine for 90 days.
STABILIZATION IN A COVERED BARNYARD
Processing in a barnyard requires a simpler plant than processing in biocells, but produces compost of a lower quality. The barnyard is a wide, open space in a shed where the compost is subjected to aerobic fermentation through the insufflation of air using an aerated bed and/or compost turning machines.
In the same way as in the biocells, after the period of active fermentation, the material must be left to mature.